Many industries utilize extrusion augers to mix and/or extrude the process materials during the manufacturing of a product. An auger is essentially a shaft having a spiraled flight that rotates to push or pull the process material axially along the auger. The process material is predominately moved by the flight because of the screw-like movement of the flight. In some industries, such as the brick industry, constituents of the process materials are very hard and/or abrasive such that the flight is worn during extensive use. Damaged or worn flights may require replacement or refurbishment for efficient operation of the auger.
Some extrusion augers include removable auger segments that provide for replacement of auger flights without replacing the entire auger. An auger segment consists of a hollow hub with a portion of the flight, such as a half or a complete revolution. The auger includes an auger shaft about which auger segments are axially attached along the auger shaft. When the auger segments are all attached, the auger defines at least one continuous flight. Auger segments with damaged or worn flight portions can be disposed of and replaced with new auger segments, or the auger segments can be refurbished for continued use.
The auger shaft typically includes a feature to prevent the auger segments from rotating relative to the auger shaft and to exert rotational force during the operation of the extrusion auger. A keyway in the auger shaft and a corresponding key or protrusion in the bore of the auger segment is one example of such a feature. A keyway can also orient the flight portions of the auger segments such that the cumulative flight(s) define a continuous surface.
Removal of the auger segments is often complicated by the process materials that pass between the auger segments during operation or by rust on the auger shaft and auger segments. The auger segments are removed axially and such debris and rust can complicate the removal of an auger segment by requiring additional force to overcome the debris, rust, or other impediments. In addition, some extruders provide limited access to the auger without major disassembly of the extruder. Thus the maintenance person who is removing the auger segments may have to pull the auger segments axially forward rather than pushing or prying the auger segments forward.
Auger segments do not have components that are inherently conducive to gripping and pulling. Gripping the flight portion results in asymmetric application of the removal forces, which increases the forces required to remove the auger segment. Since the worn flight surfaces are polished and curved they are hard to grip thus increasing the risk of injury to the maintenance personnel. Therefore, a need exists for a convenient, cost effective, and safe procedure for removing auger segments from an auger shaft without damaging the auger segments.